超声波辅助提取过程中声场的数值模拟研究

本研究建立了超声波辅助提取过程的多物理场耦合模型,将超声提取设备在一定功率不同频率下的声场分布可视化。探索不同超声频率和换能器布阵方式对声场均匀性的影响;通过比较不同频率大豆蛋白的提取率验证仿真模型的可靠性。仿真结果表明:圆筒状五频超声设备可以通过调频改善声场的均匀性,但绝对声压会随之减小;筛选出低频20 kHz及共振频率28 kHz、35 kHz处易发生空化效应,预测提取的效果较好。实验结果表明:超声处理能显著提高大豆蛋白的提取率(p0.05)且随着频率的升高效果逐渐减弱;相同条件下,20 kHz、28 kHz及35 kHz超声处理蛋白的提取率比传统碱提分别提高了28.75%、26.78%及18.28%。本研究提出工业生产中换能器矩形布阵并在共振频率处进行提取的作用效果较好。数值模拟降低了试验成本,为频率筛选、工艺优化和设备改进提供了一种新方法。

Numerical Simulation of Acoustic Field during Ultrasound-assisted Extraction

In this study, a multi-physics coupling model of ultrasound-assisted extraction (UAE) was established, to visualize the acoustic field distribution of the ultrasonic extraction equipment set at a certain power but different frequencies. The effects of different frequencies and transducer arrays on the uniformity of acoustic field were studied. The reliability of the model was verified by comparing the extraction rates of soybean protein at different frequencies. The simulation results showed that the uniformity of the acoustic field could be improved via frequency modulation by the cylindrical 5-frequency ultrasonic device, but the absolute sound pressure decreased accordingly. A low frequency of 20 kHz and resonance frequencies of 28 kHz and 35 kHz would easily cause cavitation effects, indicating an increased extraction rate. The experimental results showed that the extraction rate of soybean protein was significantly increased (p<0.05) by the ultrasonic treatment, and the increase of frequency led to a gradual decrease of extraction rate. Under the same conditions, the extraction rate of proteins sonicated at 20 kHz, 28 kHz or 35 kHz was 28.75%, 26.78% and 18.28%, respectively, higher than that obtained by traditional alkali extraction. This study also proposed that when transducers were arranged in a rectangular shape and extraction was performed at a resonant frequency, the outcome of extraction was more desirable. Numerical simulation reduces testing costs and provides a new method for frequency screening, process optimization and equipment improvement.